The present embodiments relate to an improved x-ray tube with several cathodes.
It is known in the prior art to replace conventional thermal cathodes in x-ray tubes with carbon nanotubes (CNT). CNTs can be embodied in such a way that the CNTs emit electrons by field emission and serve as efficient electron emitters for flat and self-luminous field emission displays or as cathodes in x-ray tubes.
In one known embodiment of an x-ray tube, several CNT cathodes are arranged in a tube (see Zhang, J., et al., “Stationary scanning x-ray source based on carbon nanotube field emitters.” Appl. Phys. Lett. 86, 18104 (2005)). Such a multicathode tube allows a spatial resolution, which can only be achieved with conventional single cathode tubes by mechanical displacement of the x-ray tube.
In the field of computed tomography (CT), it is desirable to integrate a large number of cathodes (e.g., 1000) in a tube. It is disadvantageous that for each cathode, which is arranged in the region of the tube under vacuum, a feedthrough toward the outside to a control unit is provided. The feedthroughs are problematic because the feedthroughs have a high withstand voltage. Typical voltages that occur amount to between 0 and 5 kV.